I don't imagine that Box Kitchen gets many walk-by customers. Located down a narrow alley off of Sixth Street, one of the grittiest blocks in San Francisco, it's not in a strolling-about sort of neighborhood. But if you find your way to Box Kitchen, you'll discover a worthwhile gastropub burger.

Making it just a little harder to find, Box Kitchen Box Kitchen doesn't get the marquee above the door. Rather, the space belongs to Tempest Bar, a dive bar with a pool table, stained glass light fixtures, and some wooden accents left behind from grander times. Box Kitchen provides the in-house menu for Tempest, things like a braised short rib sandwich or pork adobo tacos. During my lunchtime visit, the crowd inside seemed to be there mostly for the food, with office types that had walked over from the Financial District. At night, the scene shift towards booze, and Box Kitchen serves its menu through a window in the side of the building.

The Box Burger ($8) takes plenty of explaining on the menu. Box Kitchen uses ground chuck from Schmitz Ranch, which proved flavorful, though I found the grind too fine and a bit short on fat. The beef gets drizzled in a bacon-shallot gastrique that, besides adding flavor, also compensates well for what the meat lacks in moisture. Box Kitchen tops its patty with a lightly sharp white cheddar and fried shallot strings that add some salt and crunch. It all goes on a potato-pepper bun, which sounds odd conceptually, but I liked the wisp of peppery flavor hiding within. More importantly, the airy bread holds up to the eating. Despite all the components, Box Kitchen's burger avoids feeling overwrought, coming together for a very solid lunch.

Potato skins instead of fries, perhaps?

The fries (+$2) at Box Kitchen come out looking overdone, as if you'll encounter crunchy, dry potato sticks. They taste somewhat better than they look, with a bit of soft starch remaining inside and plenty of salt on the outside. But after perusing the menu, you may be inclined to skip the fries anyway. Box Kitchen makes chorizo taquitos and wings, as well as potato skins ($9): little potatoes that had been hollowed out and larded with pork belly and a tangy-rich combination of gouda cheese and crema, all prettily topped with a quail egg.

You don't expect to find a burger in this location, certainly not the bedecked offering at Box Kitchen. The fact that it's really quite good only adds to the surprise. Maybe we should all be walking down lonely alleys more often.

About the author: David Kover lives in San Francisco with his wife and 17-month-old son. He writes about burgers and pizza for Serious Eats, but tonight he's having pelmeni and borscht for dinner. He occasionally gets his tweet on at @pizzakover.